Saw elements

ABSTRACT

A saw element in which an elongate carrying member for example a wire has threaded thereon a plurality of hard beads free to rotate on the wire and having outer abrasive surfaces which are convex in the direction of the carrying member, with these abrasive elements which preferably include diamond particles as an abrasive medium being interspersed with non-abrasive spacer elements which grip the wire.

United States Patent Prowse et al.

[451 May 9,1972

[ SAW ELEMENTS [72] Inventors: Derek Henry George Prowse; Stephen DerekProwse, both of Marina-Di-Carrara, Italy [73] Assignee: IndustrialDistributors (Sales) Limited,

London, England [22] Filed: Oct. 7, 1969 [21] Appl.No.: 864,506

2,773,495 12/1956 Lefevre 125/21 2,679,839 6/1954 Metzger ..125/21FOREIGN PATENTS OR APPLICATIONS 907,347 10/1945 France ..125/21 816,6317/1959 Great Britain. 1,088,408 9/1960 Germany 1 25/21 PrimaryExaminer-Harold D. Whitehead Att0rneyl-lolman & Stern 57 ABSTRACT A sawelement in which an elongate carrying member for example a wire hasthreaded thereon a plurality of hard beads free to rotate on the wireand having outer abrasive surfaces which are convex in the direction ofthe carrying member, with these abrasive elements which preferablyinclude diamond particles as an abrasive medium being interspersed withnon-abrasive spacer elements which grip the wire.

10 Claims, 4 Drawing Figures PATENTEDMAY 9 1912 3.661 L137 FIGZ.

DEREK HEN GEORGE a) M05125 ET AL SAW ELEMENTS BACKGROUND OF THEINVENTION This invention relates to saw elements particularly useful inthe cutting of stone, marble, granite, refractories, plastics,fiberglass, metals, ceramics and other materials.

Marble, for example, is commonly cut at a quarry face or in a cuttingworks by means of an endless wire using an abrasive slurry as a cuttingmedium. This is a slow process, and one object of the present inventionis to provide ameans for cutting marble, rock and the like at a quickerrate.

SUMMARY OF THE INVENTION The invention provides, according to one of itsaspects, a saw element in the form of an elongate carrying member suchas a wire, and abrasive impregnated or abrasive coated hard beadsthreaded onto the wire, with the beads having a convex outer abrasivesurface portion in the direction of extent of the carrying member andbeing free to rotate on the carrying member.

The abrasive elements may be interspaced with non-abrasive elements,each of which is fixed to the carrying member, thereby allowing freedomof rotational, but not lateral movement, of the abrasive elements.

The abrasive impregnated or coated beads may each be spherical, barrelor ellipsoidal in shape with an axial threading bore, they may havenon-abrasive carrying end portions, and may be coated byelectrodeposition or by other means with an abrasive which could beboron or other carbide, carborundum material, but preferably theabrasive is wholly or in part constituted by natural or syntheticdiamond particles. The size and'amount of abrasive particles in thebeads will be dependant on the cutting application.

The invention provides, according to another of its aspects, for thebeads to be impregnated with abrasives of a similar nature to those usedin the electrodeposition process. Altematively, the beads may be surfaceset with large abrasive particles when the nature of the material to becut demands the use of large protruding particles.

The methods by which the abrasive elements are manufactured can varyaccording to the type of material to be cut. W hen using anelectrodeposition method for the abrasive, it is considered moreefficient to manufacture a length of shaped material such as brass,steel or a combination of metals, and after plating with abrasive, cutthe individual beads from the plated length. This method could also beused for impregnated elements where a sintered or infiltrated castlength of abrasive impregnated metal would afterwards be cut intoindividual beads, although it is considered that a more economicalmethod of manufacture for sintered or infiltrated beads would be to usean automatic casting machine manufacturing individual beads with castouter convex surfaces.

When using surface set abrasives including diamond, the abrasive wouldbe set in a mold or molds shaped to form the contours of the requiredelement, after placing the abrasive in position, the mold would befilled with metal powder, (this powder varying in particle sizeandconstituency according to the abrasive resistant qualities required),and afterwards, pressed heated to a temperature consistent to thematerial being sintered or infiltrated in an atmosphere also suitableforthat material.

The material of the carrying member on which the beads or elements arethreaded, can be single or multistrand wire, nylon or any other materialwhich will withstand a static tension and cutting pressure. A lowstretch coefficient is useful but not essential. The diameter of thematerial carrying the elements may vary according to the material to becut, the tension required, the cutting pressure and the degree offlexibility desired.

It is contemplated that the major use of the element will be :in theform of an endless saw, but other uses are considered, whereby a wire orrod of various materials is fitted with abra- 5N6 and non-abrasiveelements and used with a reciprocal motion for cutting.

According to a further feature of the invention, the saw element may,depending on the use to which it is to be put, include furthernon-abrasive including beads on and gripping the carrying element,non-abrasive beads or groups of nonabrasive beads being interposedbetween abrasive beads or groups of abrasive beads. The non-abrasivebeads grip the wire to prevent loss of beads if the wire should breakand to prevent the wire from sliding longitudinally in the beads. In acomplete saw element there should be sufficient beads so that thespacing between adjacent beads permits rotation of the abrasive beadswhile substantially preventing longitudinal movement of the beads alongthe wire.

Accordingly, a preferred form of cutting tool accordi-ng to theinvention will be composed of the following items:

1. A flexible wire, rod or like elongate carrying member manufactured toan arbitrary length. 1

2. The abrasive elements which shall be freeto rotate on the carryingmember (1), and

3. Non-abrasive elements which are interspaced between those withabrasive and fixed to the carrying member l l by means of crimping,welding, brazing, or in the case where nylon or plastic carrying wiresor rods are used. with a suitable jointing or adhesive compound.

In the case of an endless carrying member, a method of joining the endsof the wire or other material must be used. This, of course, would varyaccording to the material, but crimping, splicing, welding or brazing isconsidered the most suitable with provision for a combination of thesemethods. An adhesive compound could be used when the carrying element isof nylon or a plastic material.

The shape of the non-abrasive elements is relatively unimportant, astheir main purpose is to provide for a space between the abrasiveelements and to prevent the abrasive ele-' ments moving laterally alongthe carrying member. It is considered, in particular to the endlesswire, that the shape of the non-abrasive elements should be such, that aconvex surface is presented to a pulley carrying the wire and to thematerial being cut to prevent any percussive movement or vibration.

The convex shape of the abrasive elements is essentially universal forall applications, but in the case of cutting highly abrasive softmaterial where it is necessary to have an unusual degree of protrusionof the diamond or other abrasive particles, then the surface of theabrasive element or bead can be varied to provide this feature.

The number of non abrasive elements used in proportion to those carryingabrasive, can be varied according to the material to be cut and theperipheral or surface speed of the wire in proportion to the requiredfeed rate. The length of the individual nonabrasive elements or beadscan also be varied for a similar reason.

Depending on the cutting application, single abrasive beads mayalternate on the wire with single non-abrasive beads, or groups of onetype of bead may alternate with groups or single beads of the othertype.

It is expected, that when cutting any material, the convex outer shapeof the abrasive beads and their freedom to rotate will minimize thepercussive effects at the edges of the material, and also by rotatingwill utilize the whole of the abrasive surface. The element will be usedwith a non-abrasive lubricant.

The invention will now be described by way of an example with referenceto the accompanying drawings which are sectional side views of fouralternative types of cutting element.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view partly in elevationand partly in cross-section of a saw element, and

FIGS. 2-4 are views similar to FIG. 1 several embodiments of theinvention.

DETAILED DESCRIPTION OF THE EMBODIMENTS In FIG. 1, barrel shapedabrasive coated elements 1'. are threaded on a wire 2, with theseelements being free to rotate on the wire and being interspersed withnon-rotary non-abrasive carrying elements 3 crimped on the wire to gripthe same.

(For example, a non-abrasive element having an axial bore may beradially slit to position it on the wire between a pair of abrasiveelements and then crimped onto the wire).

In FIG. 1 abrasive particles extend over substantially the entire outersurface of elements 1 and it will be seen that the abrasive particles,when rotating, would tend to abrade the crimped, non-abrasive elements3. Two methods may be used to prevent this occurring as follows:

As shown in FIG. 2, the abrasive particles on the abrasive elements laare prevented from touching the non-abrasive elements 3a by stopping theabrasive particle coverage of elements 1, before the end of the abrasiveelement, thus producing a plain non-abrasive bearing surface 4. Tofurther aid the free running movement of the abrasive element, thenon-abrasive element can be made in three sections 3b, 3c and 3d asshown in FIG. 3, with the two outer sections 3b and 3d being free torevolve while the center non-abrasive section 30 remains fixed to thecarrying member 2 Le. the wire, cable or cord.

As shown in FIG. 4, the abrasive particles on the abrasive elements 12are prevented from touching the non-abrasive elements 3e by restrictingthe abrasive particle coverage, before the end of the abrasive element,thus producing a plain nonabrasive bearing surface 5. To restrict thefree running movement of the abrasive element, each end of theseelements thus has a male cone a fitting which corresponds with a similarfemale cone fitting 5b in the fixed, non-abrasive elements. Thus, whileunder cutting pressure, the abrasive elements would be prevented fromrotating by this cone clutch method, and wear through friction wouldalso be reduced.

In the event of it being necessary to reduce the number of abrasiveelements in proportion to those carrying abrasives, the additionalnon-abrasive elements will be fitted in the manner of the abrasiveelements incorporating the design shown in FIGS. 2 to 4 or a combinationof such designs.

Saw elements according to the invention can have an infinite variationin length, diameter of element and diameter of carrying element. It isenvisaged that such saw elements will have three major uses:

l. The cutting of geological materials in situ as in the case of mining,tunnelling and quarrying. The wire and elements will, in this case,revolve around two pulleys, one of which will have a cutting face andthe other will be driven by a motor having electricity, air or aninternal combustion engine as the motive power unit. The cutting pulleyand wire will be fed into the material by screw or hydraulic means andafterwards moved in the required direction by similar means.

. The cutting of blocks of stone, marble, granite, refractory, graphiteetc., when the wire and elements will revolve around two or more pulleyswhich can be moved downwards by means of a screw or hydraulic feed unit.The material which shall be placed under the wire between the pulleys,shall be cut freely by the wire during its descent. It is envisaged thatin this application, multiple pulleys will be employed in order toproduce a number of cuts during one descent of the machine.

3. The cutting of plastics, fiberglass, hard metals or the like. with asmall machine which can be hand held or used as part of an existingcutting machine. The wire and cutting elements to be used in either arotary motion, revolving around two pulleys, or in a reciprocatingmotion.

All the above methods can be used with either air, water, or

oil as a coolant.

The endless element or reciprocating wire is less susceptible to selfabrasion than any present method in use, and the whole of the abrasivearea can be fully utilized.

We claim:

1. A saw element for use in the cutting of stone, marble, refractories,plastics, metals, ceramic and other materials comprising an endlessflexible carrying member abrasive elements in t e form of hard beadsloosely threaded on the carrying member, said beads each having an outerabrasive surface portion, said outer abrasive surface portion beingconvex in the direction of extent of the carrying member, and discretenon-abrasive elements between at least some of said abrasive elements,the non-abrasive elements gripping the carrying member to preventrelative rotation between the non-abrasive elements and the carryingmember while maintaining the abrasive elements in spaced apartrelationship for freedom of rotational but not lateral movement relativeto the carrying member.

2. The saw element as claimed in claim 1 wherein said abrasive elementsare abrasive coated to provide said surface outer abrasive surfaceportion.

3. The saw element as claimed in claim 1 wherein said abrasive elementsare abrasive impregnated.

4. The saw element as claimed in claim 1 wherein said abrasive elementsinclude diamond particles as an abrasive medi- 5. The saw element asclaimed in claim 1 wherein said abrasive elements are provided withopposite end portions free of abrasive elements, with said end portionspreventing the outer abrasive surface portion of the abrasive elementsfrom touching the non-abrasive elements.

6. The saw element as claimed in claim 5 wherein said outer surfaceportion is barrel shaped and said opposite end portions are non-barrelshaped extensions of said outer surface convex portion.

7. The saw element as claimed in claim 1 wherein said nonabrasiveelements are crimped onto the carrying member.

8. The saw element as claimed in claim I wherein said nonabrasiveelements have concave end portions complementary to the end portions ofadjacent abrasive elements.

9. The saw element as claimed in claim 1 wherein each of saidnon-abrasive elements includes a center section gripping the carryingmember and two outer sections capable of rotation on the carryingmember.

10. The saw element as claimed in claim 1 in which said non-abrasiveelements each have an outer surface which is convex in the direction ofextent of the carrying member.

1. A saw element for use in the cutting of stone, marble, refractories,plastics, metals, ceramic and other materials comprising an endlessflexible carrying member, abrasive elements in the form of hard beadsloosely threaded on the carrying member, said beads each having an outerabrasive surface portion, said outer abrasive surface portion beingconvex in the direction of extent of the carrying member, and discretenon-abrasive elements between at least some of said abrasive elements,the non-abrasive elements gripping the carrying member to preventrelative rotation between the non-abrasive elements and the carryingmember while maintaining the abrasive elements in spaced apartrelationship for freedom of rotational but not lateral movement relativeto the carrying member.
 2. The saw element as claimed in claim 1 whereinsaid abrasive elements are abrasive coated to provide said surface outerabrasive surface portion.
 3. The saw element as claimed in claim 1wherein said abrasive elements are abrasive impregnated.
 4. The sawelement as claimed in claim 1 wherein said abrasive elements includediamond particles as an abrasive medium.
 5. The saw element as claimedin claim 1 wherein said abrasive elements are provided with opposite endportions free of abrasive elements, with said end portions preventingthe outer abrasive surface portion of the abrasive elements fromtouching the non-abrasive elements.
 6. The saw element as claimed inclaim 5 wherein said outer surface portion is barrel shaped and saidopposite end portions are non-barrel shaped extensions of said outersurface convex portion.
 7. The saw element as claimed in claim 1 whereinsaid non-abrasive elements are crimped onto the carrying member.
 8. Thesaw element as claimed in claim 1 wherein said non-abrasive elementshave concave end portions complementary to the end portions of adjacentabrasive elements.
 9. The saw element as claimed in claim 1 wherein eachof said non-abrasive elements includes a center section gripping thecarrying member and two outer sections capable of rotation on thecarrying member.
 10. The saw element as claimed in claim 1 in which saidnon-abrasive elements each have an outer surface which is convex in thedirection of extent of the carrying member.